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Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and an AAO frame, the NF-A4x20 5V PWM is a PWM enabled 5V variant of Noctua’s highly optimised, premium quality quiet 40x20mm fan. The custom designed NE-FD3 PWM IC that integrates Smooth Commutation Drive technology and Noctua’s reference class SSO2 bearings guarantee superb running smoothness and excellent long-term stability. Topped off with modular cabling, the OmniJoin™ Adaptor Set and 6 years manufacturer’s warranty, the NF-A4x20 5V PWM is a premium choice for demanding 5V applications that require PWM control.
Being a 5V fan, the NF-A4x20 5V PWM cannot be run at 12V and will be damaged when used with typical 12V power sources such as PC motherboard fan headers.
Details
40x20mm size

40x20mm size

Compared to Noctua’s award-winning NF-A4x10, the NF-A4x20 is twice as thick, which allows for increased static pressure performance and makes the NF-A4x20 ideal for demanding applications with high flow resistance.
5V PWM version

5V PWM version

Many devices such as network or storage solutions use 5 volt 40mm fans with PWM speed control. With the same operating voltage, PWM support and the included OmniJoin™ adaptor set that makes it compatible with proprietary fan headers, the NF-A4x20 5V PWM is ideal for replacing noisy or broken 5V 40mm fans with PWM.
Polarity protection

Polarity protection

As many devices using 5V fans feature proprietary connectors and documentation of the pin alignment may not be available, the fan features an integrated diode for polarity protection. This way, you're on the safe side if you accidentally connect it with reverse polarity.
Flow Acceleration Channels

Flow Acceleration Channels

The NF-A4x20 impeller features suction side Flow Acceleration Channels. By speeding up the airflow at the crucial outer blade regions, this measure reduces suction side flow separation and thus leads to better efficiency and lower vortex noise.
AAO frame

AAO frame

Noctua's AAO (Advanced Acoustic Optimisation) frames feature integrated anti-vibration pads as well as Noctua's proprietary Stepped Inlet Design and Inner Surface Microstructures, both of which further refine the fan's performance/noise efficiency.
Stepped Inlet Design

Stepped Inlet Design

Noctua's Stepped Inlet Design adds turbulence to the influx in order to facilitate the transition from laminar flow to turbulent flow, which reduces tonal intake noise, improves flow attachment and increases suction capacity, especially in space-restricted environments.
Inner Surface Microstructures

Inner Surface Microstructures

With the tips of the fan blades ploughing through the boundary layer created by the Inner Surface Microstructures, flow separation from the suction side of the blades is significantly suppressed, which results in reduced blade passing noise and improved airflow and pressure efficiency.
Integrated Anti-Vibration Pads

Integrated Anti-Vibration Pads

Integrated Anti-Vibration Pads made from extra-soft silicone minimise the transmission of minute vibrations while maintaining full compatibility with all standard mounting systems and fan clips used on heatsinks.
Custom-designed PWM IC with SCD

Custom-designed PWM IC with SCD

Supporting fully automatic PWM speed control, the fan uses Noctua's custom-designed NE-FD3 5V PWM IC that integrates Smooth Commutation Drive (SCD) technology. By providing smoother torque impulses, SCD suppresses PWM switching noises and thus makes the fan quieter at low speeds.
OmniJoin™ adaptor set

OmniJoin™ adaptor set

Many devices featuring 40mm fans use proprietary fan headers, so the NF-A4x20 comes with Noctua's OmniJoin™ adaptor set. Just cut the original fan's cable, fix it to the adaptor using the supplied 3M Scotchlok™ connectors and you can plug the NF-A4x20 to proprietary fan headers!
Extensive cabling options

Extensive cabling options

The fan's short 20cm primary cable minimises cable clutter in typical applications while the supplied 30cm extension provides extended reach when necessary. Both cables are fully sleeved and a 4-pin y-cable allows the connection of a second fan to the same PWM fan header for automatic control.
SSO2 bearing

SSO2 bearing

The NF-A4x20 features the further optimised second generation of Noctua's renowned, time-tested SSO bearing. With SSO2, the rear magnet is placed closer to the axis to provide even better stabilisation, precision and durability.
6-year manufacturer’s warranty

6-year manufacturer’s warranty

Noctua fans are renowned for their impeccable quality and outstanding longevity. Like all Noctua fans, the NF-A4x20 features an MTTF of more than 150.000 hours rating and comes with a full 6-year manufacturer’s warranty.
NF-A4x20 5V PWM
General
Notes and warnings
Being a 5V fan, the NF-A4x20 5V PWM cannot be run at 12V and will be damaged when used with typical 12V power sources such as PC motherboard fan headers.
FAN Specification
Size
40x40x20 mm
Mounting hole spacing
32x32 mm
Connector
4-Pin PWM
Bearing
Blade Geometry
Rotational Speed (+/- 10%)
5000 RPM
Min. Rotational Speed (PWM, +/-20%)
1100 RPM
Acoustical Noise
14,9 dB(A)
Static Pressure
2,26 mm H₂O
Max. Input Power
0,5 W
Max. Input Current
0,1 A
Voltage
5 V
MTTF
> 150.000 h
Scope of delivery
  • 4-pin y-cable
  • 30cm extension cable
  • OmniJoin™ adaptor set
  • NA-AV3 anti-vibration mounts
  • Fan screws
Warranty
6 years
NF-A4x20 5V PWM
A-Series fans
Video Reviews
The following video reviews have not been created by Noctua. Responsibility for the information and views expressed in the videos lies entirely with the authors.
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19.09.2017 // pcfoster.pl
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NF-A4x20 5V PWM Review

Wielu konkurentów nie daje wraz ze swoimi urządzeniami niezbędnych akcesoriów przez co jesteśmy narażeni na dodatkowe koszty. Tutaj ten problem nie występuje. Widać, że Noctua przez ponad 12 lat obecności na rynku wykonała wspaniałą pracę i udowodniła, że nawet najlepsze produkty można poprawić. Urządzenia z serii A wyróżniają się przede wszystkimi nowymi technologiami, niskim poziomem hałasu, wysokim przepływem powietrza i przede wszystkim świetnym wykonaniem. Modele A12x15 są ciche, solidne i mają tylko 15 mm grubości, za to A20 sprawdzą się w dużych obudowach, gdzie potrzebny jest duży przepływ powietrza. Małe modele A4x20 są przeznaczone głównie dla środowisk specjalistycznych, a dzięki adapterowi OmniJoin można je wszechstronnie wykorzystać.
Test verdict: "Powyższy artykuł powinien Was tylko utwierdzić w przekonaniu, że produkty austriackiej firmy są w rzeczywistości najwyższej jakości. Każdy z nich został świetnie zaprojektowany i dostarczany jest w bogatym zestawie." (Marcin Jankowski, pcfoster.pl)
18.09.2017 // PCElite.pl
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NF-A4x20 5V PWM Review

Ceny za każdy produkt tej firmy są wysokie jednak idzie za tymi cenami jakość wykonania, przemyślana konstrukcja, solidność. Te cechy maja odzwierciedlenie wszędzie, w każdym detalu, nawet w szczegółach związanych z opakowaniem, ze sposobem zaciśnięcia termokurczek. Jedynie do czego mogę się przyczepić to kolorystyka (jedni chwalą jak ja, drudzy ganią) oraz cena.
Test verdict: "Długo myślałem nad podsumowaniem jednak opiszę to krótko – Noctua to Noctua. Dobrze wydane pieniądze." (Arkadiusz Byś, PCElite.pl)
11.09.2017 // Tecnogeekies.com
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NF-A4x20 5V PWM Review

Hoy hemos presenciado como Noctua lo ha vuelto a hacer, las prestaciones de sus nuevos productos continúan siendo la referencia que siempre han sido, pero hay otras cosas que también van a continuar. Frente a las grandes prestaciones tradicionales de Noctua hay otro aspecto que también se mantiene, este nivel de calidad no es barato, desde los 30€ que cuesta el ventilador de 200mm, el NF-A20. El adaptador SATA por 8€, el controlador por 20€ o los sorprendentes 15€ que cuesta el pequeño ventilador de 40mm, pasando por los más razonables 20€ por el ventilador más tradicional de 120mm. No obstante hemos de hacer hincapié en algo que solemos decir en Tecnogeekies bastante a menudo, aunque 20€ pueden parecer muchos, especialmente solo por un ventilador, su calidad y su durabilidad nos hacen recomendar esta marca siempre que vuestro presupuesto os lo permita.
Test verdict: "La calidad tiene un precio, pero en casos como el de Noctua merece la pena." (Ignacio Merino, Tecnogeekies.com)
10.09.2017 // EnlaceHW.com
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NF-A4x20 5V PWM Review

Los ventiladores Noctua NF-A4x20 llegan a un nicho de mercado donde la competencia es prácticamente, nula. Pero no es la falta de competencia, lo que los convierte en una buena opción de compra, sino la presencia de las tecnologías exclusivas de Noctua. Las prestaciones técnicas de los NF-A4x20 son extraordinarias. Durante las pruebas se desempeñaron de manera asombrosa, lo que nos asegura un rendimiento impecable en situaciones donde se requiera de una solución confiable de disipación, como, por ejemplo, en el ámbito de los servidores o en sistemas avanzados donde el espacio sea sumamente reducido. Pero su aplicación no se limita al ámbito de hardware, sino que también se puede emplear para ventilar dispositivos como conmutadores, ruteadores, grabadores de vídeo digital y otros dispositivos.
Test verdict: "Las cuatro versiones del ventilador NF-A4x20 llevan una etiqueta de precio de 265 pesos mexicanos antes de impuestos. Los NF-A4x20 son los mejores ventiladores de 40mm que existen en el mercado actual gracias al alto nivel de calidad y rendimiento que ofrecen. Por si no fuera suficiente, los ventiladores cuentan con un inigualable respaldo de parte de Noctua, quien ofrece una generosa garantía de seis años."
30.08.2017 // Conseil Config
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NF-A4x20 5V PWM Review

En ce qui concerne le niveau sonore la marque a bien travaillé, les NF-A4 se démarquent de ce que l'on trouve habituellement avec une discrétion très apréciable, les NF-A12 quant à eux sont très silencieux au minimum mais plutôt bruyant une fois alimentés en 12V, rien de bien grave cela dit vu les adaptateurs livrés. Les plus gros NF-A20 sont également silencieux que ce soit au minimum ou au maximum. Proposés à un tarif allant de 7.90€ pour les NF-A4 à 29.90€ pour les NF-A20 en passant par 19.90€ pour les NF-A12x15 ils sont encore une fois réservés à ceux qui ne se satisfont que de produits haut de gamme, ils ne seront clairement pas déçus.
Test verdict: "Chez Noctua le maitre mot est qualité, et encore une fois cela se voit sur les derniers ventilateurs de la marque." (Christian Marchini, Conseil Config)
21.08.2017 // OCKD.es
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NF-A4x20 5V PWM Review

En ventilador NF-A4x20 condensa toda la calidad que vemos en los ventiladores Noctua de gran tamaño en estas pequeñas unidades, donde no falta nada de tecnología de la que podríamos encontrar en las unidades de 120 o 140mm más habituales. Disponemos del mismo chasis AAO y rodamientos SSO2 que proporcionan baja sonoridad y anti-vibración a estos ventiladores, por si fuera poco además se han incluido patas anti-vibración, e incluso un kit de montaje anti-vibración para reducir esta a lo mínimo posible. Hay que recordar que es un ventilador capaz de alcanzar las 5000 RPM, por lo que es algo muy importante evitar cualquier tipo de ruido que provenga de vibraciones, ya que suele ser el más molesto. Por otro lado, cada uno de los modelos incluye toda una serie de accesorios para todo tipo de usos, destacando el modelo FLX que cuenta con adaptadores que nos permitirán reducir la velocidad de el ventilador, o los modelos de 5V, pensados para un uso más puramente industrial. Obviamente hemos podido encontrar dos versiones PWM tanto a 12V, como a 5V, por lo que los usuarios industriales muy probablemente preferirán la versión 5V ya que es el voltaje más utilizado en la maquinaria industrial.
Test verdict: "Cuando Noctua nos envió las samples de estos ventiladores de 40mm ya sabíamos que estábamos ante muy probablemente los mejores ventiladores de 40mm del mercado, una medida muy poco habitual pero que aquellos modders o usuarios con necesidades de tipo industriales van a agradecer." (Eloy Puigcerver, OCKD.es)
17.08.2017 // APHNetworks.com
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NF-A4x20 5V PWM Review

Noctua is well known for being quiet, but also have good performance. They have definitely stayed true to their reputation. The Noctua NF-A series have exceptional build quality through and through. All of the fans performed well during the tests. On top of that, they were also quiet, especially if run at nominal speeds instead of their maximum.
Test verdict: "The Noctua NF-A Series is a comprehensive line up of fans that will be great addition to many system environments." (Ben Joubert, APHNetworks.com)
10.08.2017 // WhatNext.pl
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NF-A4x20 5V PWM Review

Wszystkie wentylatory oraz akcesoria są godne polecenia. Noctua ponownie pokazuje, że umie zrobić świetne konstrukcje. Śmigła są wydajne i prezentują się dobrze pod względem kultury pracy. Także jakość wykonania stoi na najwyższym poziomie. Podobnie jest z akcesoriami – świetne wykonanie i odpowiednie działanie.
Test verdict: "W zakupie sprzętu przeszkadzać może jedynie cena, która jest spora. Jednakże znakomite produkty nie mogą być tanie bo było by zbyt pięknie." (Michał Andruszkiewicz, WhatNext.pl)
09.08.2017 // InsideGeeks.net
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NF-A4x20 5V PWM Review

Todas estas ventoinhas são apenas mais uma continuação do excelente trabalho que a Noctua tem vindo a fazer no que toca a cooling de pcs e tudo mais. Os seus produtos são de excelente qualidade ao qual se juntam acessórios sem fim e excelente suporte ao utilizador. Os seus preços são elevadas relativamente à concorrência, mas a qualidade também é, o que faz com que o preço se justifique e seja perfeitamente ajustado ao produto.
Test verdict: "Como sempre, as Noctua são um produto recomendado pelo InsideGeeks!" (Nuno Ferreira, InsideGeeks.net)
12.07.2017 // FunkyKit.com
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NF-A4x20 5V PWM Review

We have no doubt about the top quality of Noctua products. Each one of them is well designed. Even the package is exceptional. Most manufacturers are missing these little things that count while Noctua provides package with everything you may need for installation. Long years of designing and engeneering gave great results. Where you could think there can’t be done much more, Noctua proved that even the best products can be improved. New A series fans are the best in their class and it’s hard to find anything similar on the market. Even though new fans are considered as “slim”, they provide top air pressure while keeping low level of generated noise. Perfect balance for all who expect the best from their fans.
Test verdict: "We are recommending all new Noctua products without any hesitation!" (Bartosz Waluk, FunkyKit.com)

Installation Manual (PDF)

Information Sheet (PDF)

What pin configuration do Noctua 5V fans use?

The pin configuration of Noctua 5V fans is identical to 12V fans:

5v pin configuration

What pin configuration do Noctua 12V fans use?

All Noctua fans feature the standard pin-configurations set out in the Intel and AMD specifications. These standard pin-configurations are used on most mainboards and fan controllers today:

pin configuration

How should I clean my Noctua fan?

Fans inside computer cases tend to accumulate dust over longer periods of usage. In order to maintain maximum performance, please clean your fans regularly using a duster, slightly moist tissue or canned air. Please be careful not to use too much force in order to prevent any damage to the fan. Please do not use a vacuum cleaner as this may apply excessive force to the fan and do not put the fan under running water as water residues inside the motor may lead to short circuits.
In order to ensure flawless operation over many years of usage, Noctua’s premium grade SSO bearings are fully sealed to prevent the entering of fine dust particles. Please note that the fan is not designed to be taken apart by the user. Removing the impeller from the frame will break the sealing of the bearing and results in a loss of warranty.

Can I disassemble my fan for cleaning (or other purposes, e.g. painting)?

In order to ensure flawless operation over many years of usage, all Noctua fans come with a premium grade SSO bearing, which is fully sealed to prevent the entering of fine dust particles. Please note that the fan is not designed to be taken apart by the user. Removing the impeller from the frame will break the sealing of the bearing and results in a loss of warranty.

It is thus recommended to clean your fans using a duster, slightly moist tissue or canned air. Please be careful not to use too much force in order to prevent any damage to the fan. Please don’t use a vacuum cleaner as this may apply excessive force to the fan.

Can I run 4-pin PWM fans on 3-pin fan headers?

PWM fans come with a 4-pin connectors for fully automatic speed control via your mainboard’s 4-pin PWM fan headers. Please note that 4-pin fans can also be connected to your mainboard’s 3-pin fan headers though. When connected to 3-pin fan headers, the fan will run at full speed (unless the mainboard supports voltage based speed control).

How can I check if my 4-pin fan header supports PWM?

Some mainboards feature 4-pin fan headers that actually don‘t use a PWM signal on Pin 4 to control the fan speed but rather reduce the voltage on Pin 2 (like a standard 3-pin fan header). As the fan speed at minimum voltage is usually higher than the speed at 20% PWM duty cycle, the fan can not reach as low minimum speeds under voltage control as under PWM control. Please refer to your mainboard manual to check whether or not your mainboard has 4-pin fan headers that control the fan speed by reducing voltage on Pin 2 rather than by changing the PWM duty cycle on Pin 4:

4 pin fan header types

Note that mainboard manufacturers use different terms to indicate that Pin 4 is not being used for PWM control (e.g. “+5V”, “VCC” or “NC”), but if one of these terms is used, you can be sure that the fan header does not support PWM. If Pin 4 is described as “Speed Control” or “PWM” or the like, you can be sure that the fan header supports PWM.

Unfortunately, the description of Pin 2 is not always a clear indication as some manufacturers use terms such as “Fan PWR” or “Power” for both types of fan headers. However, if Pin 2 is described as “Speed Control”, you can also be sure that the fan header does not support PWM based speed control. If Pin 2 is described as “+12V”, this is a clear indication that the fan header supports PWM.

Please also note that in some cases, the descriptions of the pin layouts in the mainboard manuals may not be correct and some models actually allow you to switch the fan headers from voltage control mode to PWM control mode in the BIOS even though the pin descriptions do not indicate PWM support. We thus recommend to look for these options in the BIOS before taking other measures. In case of doubt, please contact your mainboard manufacturer.


If your mainboard features other 4-pin fan headers that use PWM for speed control, you can run multiple fans from these headers using Y-split cables. Make sure not to exceed the specified maximum power draw of the fan headers (usually 10-12W) though.

Can I use Noctua fans in my system from Acer, Apple, Dell, HP, Lenovo or other major brands?

Noctua 12V fans comply with the established specifications for standard PC systems issued by Intel and AMD. Systems from Acer, Apple, Dell, HP, Lenovo or other major brands often deviate from these specifications e.g. by using proprietary fan headers, custom pin-alignments or pin-configurations, different methods of fan speed control, etc. This can lead to compatibility issues when using Noctua fans in systems from said brands. Some of these problems can be avoided with some technical knowledge, but especially BIOS related issues (e.g. errors or shutdowns due to low fan speed) can often not be resolved. As a result, Noctua does not officially support systems from Acer, Apple, Dell, HP, Lenovo or other major brands.

Can Noctua fans be used to replace noisy stock fans in NAS devices?

Noctua fans such as the 40, 60, 80 or 92mm NF-A series models are ideal for replacing noisy stock fans in NAS devices in order to make them quieter and thousands of users have managed to significantly reduce the noise levels of their NAS units this way. However, while it is easy and straightforward to replace the fans in some cases, it can be very difficult in others, so Noctua strongly recommends that users carefully research if it is possible to easily replace the fan(s) of their NAS device before purchasing a Noctua fan for this purpose. Some of the common issues that can occur when replacing NAS fans are:

  • Different pin assignment: Whereas Noctua fans use the standardised pin assignment for PC fans (see this FAQ for details), some NAS units use different assignments. For example, some devices have the power and GND or rpm and PWM pins swapped. Therefore please carefully verify that your NAS device uses the same pin assignment as standard fans. Experienced users may also change the pin assignment by cutting and resoldering the fan cables, but please note that this will void your Noctua manufacturer’s warranty.
  • Different pin functions: Noctua fans use the standardised pin functions for PC fans (see this FAQ for details); however, some NAS units use fans where certain pins serve a different function. For example, some devices use the RPM pin for “power good” signals. Therefore please carefully verify that your NAS device uses the same pin functions.
  • Firmware speed control: Some NAS devices demand a certain maximum or minimum fan speed. If the new fan doesn’t have the same or similar maximum or minimum speed, the device may display errors or even shut down.
  • Different starting voltage: Most NAS devices use voltage-based speed control. If the new fan has a higher starting voltage than the original fan, it may not start up right away. This may lead the NAS device to display errors or even shut down because it suspects a fan failure.
  • Different power draw: Some NAS devices monitor the fan’s power draw. If the new fan has a lower power consumption than the stock fan, the device might display errors or even shut down.

Please note that most NAS manufacturers don’t provide detailed documentation regarding fan compatibility and control, so users who want to replace the fans of their devices usually have to rely on “How to” guides, blog and forum posts or video tutorials. For example, there are excellent video tutorials available for changing the fans in popular Synology NAS models (DS416j, DS1515+ and DS1812+ in English, DS416/DS415/DS916/DS216/DS214 and DS1515+ in German). Please also note that fan compatibility and control can vary from model to model and even from revision to revision even if the devices stem from the same manufacturer. As a result, it is important to make sure that the information or guidelines you rely on when replacing your NAS fan are applicable to your specific model as well as your specific hardware and firmware revision.

Due to the possible issues listed above, Noctua recommends that only experienced users attempt to replace their NAS fans. Please note that since there are so many different NAS models and most of them lack documentation for aspects such as fan compatibility and control, Noctua customer support cannot assist you with compatibility issues when replacing NAS fans. Please contact your NAS manufacturer for any questions regarding aspects such as the device’s pin alignment or fan monitoring and control.

Can I use Low-Noise Adaptors with y-cables / multiple fans?

Yes, Low-Noise Adaptors (L.N.A.s) can be used with y-cables, but please make sure to use one L.N.A. per fan and to place the L.N.A.s between the y-cable and the fans as shown below. Never use one L.N.A. for two (or more fans) by placing it between the mainboard and the y-cable!

D15S

Which Noctua fan or CPU cooler should I buy? How to choose the right model?

Not sure which Noctua product to buy? Our detailed buying guides for fans and CPU coolers help you to choose the model that works best for you.

Do you have a question concerning one of our products? Please use this form to pose a question!